Briqueting iron ores.



vm n erate rare-Fur oF wamnnn MATHESIUS, or cnsnnorrnnsune, Gunnery.

BBIQUETING IRON ORES.

1,104,124. No Drawing.

To all whom it may} concern Specification of Letters Batent. u ncationmenus 22, 1913.

Be it known that I, WALTLEIER Marnusms, subject of the Kingvof Prussia,residing .at'. 10 Carmerstrasse, Gharlottenburg, near Berlin, GermanEmpire, have invented certain new. and useful Improvements inBriquetinglron Ores, of which the following is a specification.

This invention relates to improvements in the manufacture of briquetsfrom finelydivided iron ores, blast furnace fine dust and.

the like for smelting purposes. Hitherto it has been proposed to use anadmixture of finely ground quartz and lime or to use cement as thebindingmedium and to sub- Ject the mass, after being molded in .a press,to steam under pressure for a period of about 10 hours, hydro-silicatesbeing thereby formed which effect the binding of the particles with oneanother. These processes, however, necessitate the use of ".aconsiderable quantity of the binding medium, thus reducing thePercentage of iron in the finished briquet. Moreover the binding mediummay be expensive. Experiments have shown that a large'quantity of thebinding medium is necessary owing to the fact that the silicates presentin fusions such as cement or blast furnace slag are dissociatedextremely slowly under the action of water.

It has therefore been proposed to facilitate the dissociation of thesilicates by subjecting the materialsto be briqueted, before beingpressed, to the action of steam at a somewhat lower pressure and for asomewhat shorter period of time than subsequently employed inaccelerating the setting operation.

The present invention consists in the employment of a binding mediumwith which: part of the iron oxid contained in the materials to bebriqueted is capable of reacting,

the binding medium being obtained from' alumino-sihcates of such highlybasic properties that iron oxid is capable of reacting therewith, thatis to say, alumino-silicatesv such a are obtained as the products ofcalcining or fusion, containing a high percentage of lime with orwithout, other bases.

According to the presentinventioutheg highly-basic alumino-silicates are.mlxedi with ferric hydroxid in the presence of Patented July 21., iota.Serial No. 780,480.

water. It is found that in this manner a binding medium is obtainedconsisting of complex compounds of lime, alumina, silica, and ferrichydroxid and that, if the addition of ferric hydroxid has not exceeded acertain limit, this binding medium will react with further quantities offerric hydroxid or ferric 'oxid and, on setting, yield productsinsoluble in water and having setting properties similar to cement: Itis necessary, however, to mix the binding medium in as fresh .a state aspossible with the material to be briqueted. The binding medium shouldpreferably be prepared from highly small amount of silica is present inproportion to the amount .of alumina, since the aluminates can be muchmore easily liberated v\by the action of' water than the sillcates. Incarrying out the .aforesaid process the highly basic .alumn-io-silicatesin pulverized form are first of all mixed with ferric hydroxid in \theproportion of about one molecule .of ferric rhydroxid to three molecules,of the bases contained in the al-uminoesilicatesg'as for example,- 3CaOto 1Fe OH) and thereupon moistened with hot water. After intimatemixture and a moderate period of reaction, not exceeding a few hours,the binding medium so formed is mixed with the iron ores. or flue dustor othermaterial tobe briqueted and, moistened with hot water ifnecessary, 'is molded in a press. In the course of a few hours, settingtakes place. If carefully carried out, the addition of about 1 to 2% ofthe aluminosilicates i sufficient to produce sufficiently firm briquets.

Any highly basic alumino-silicate may be employed for the bindingmedium, as for example, Portland cement, blast furnace slag or likeproducts of calcination or fusion to which the necessary quantity oflime or other base has been added.- In most cases, however, it will befound cheaper to use ordinary burnt lime which is also a highly basic.alumino-silicate, since tl'l6 ordinary 5 lime-stone contains a smallquantity of silica and alumina as impurities. If burnt or ground causticlime, or caustic lime obtalned in a finely-divided state by dry slakingor basic alumino-silicates in which onlya v in the form of milk of limeis used in the aforesaid process, the setting reaction between the limeand ferric hydroxid is so intense during the preliminary mixingoperation that every particle of lime is immediately surrounded by anenvelop of ferric hydroxid which retards the further advance of thereaction. It is therefore necessary in thi case to effect the intimatemixture of the materials by means of a Wet grinding operation with orwithout the applicatfon of heat.

Preferably, in carrying out the latter process ordinary burnt limecontaining small quantities of alumina and silica is mixed withfinely-divided iron ore and subjected to a wet grinding and mixingprocess. The mixture may then be heated to accelerate the reaction ofthe iron oxid with the lime and the binding medium so obtained is mixedin a fresh state with granular iron-ore so as to react therewith, themixture being moistened if necessary and thereafter molded into briquetsand allowed to set.

In the processes according to the present invention hereinbefore setforth it will-be noted that the binding medium consists largely of limeand since lime is entirely unsuitable as a cement, it follows that thebinding medium is not a cement, having no binding properties in itself,but that, in combinationwith iron-ore, it forms a kind of iron cement,the iron acting in a similar manner to the aluminium in Portland andlike cement. I

As already described, the highly basic alumino-silicates react with theiron ore in two stages, being first caused to combine with a smallquantity of iron ore in a preliminary stage and then to combine with afurther quantity of iron ore in subsequent stage of the process. v

If briquets manufactured as above described were fused in a blastfurnace, the expulsion of the water and the decomposition of thealuminates and silicates which effect the setting would take' place at atemperature of about 1,000 to l,100 C. The briquet would thereforedisintegrate at this temperature unless the materials agglomerated.

Inasmuch as the fusing point of cement and ferrites containing a highpercentage of lime, corresponding say to the formula 3CaOFe O exceeds1500 C. and as these substances even when mixed fuse at temperatures ofabout 1200 to 1300 (1., it is necessary to reduce the fusing point ofthe highly basic binding medium. This may be effected by adding smallquantities of other bases, such as magnesium oxid, strontium oxid,barium oxid, or the like and introducing similar small quantities ofsimilarly reacting acids such as titanic acid.

I claim 1. Method of briqueting finely-divided iron ores, blast-furnacefine dust and the like which consists in forming a binding mediumcontaining a base, alumino-silicates and iron oxid by mixing pulverizedhighly basic alumino-silicates with ferric hydroxid and Warm water,mixing the binding medium with the material to .be briqueted and moldingthe whole.

2. Method of briqueting finely-divided iron ores, blast-furnace fluedust and the like which consists informing a binding medium containing abase, alumino-silicates and iron oxid by mixing pulverized highly basicalumino-silicateswith ferric hydroxid and warm water in the proportionof about one molecule of ferric-hydroxid to three molecules of the basescontained in the basic alumino-silicates, mixing the binding medium withthe material to be briqueted and molding the whole.

3. Method of briqueting finely-divided iron ores, blast-furnace fluedust and the like which consists in forming a binding medium containinglime, alumino-silicates and iron oxid b mixing caustic lime containingalumino-silicates with ferric hydroxid by wet grinding, thereupon mixingthe bindlng medium with the material to be briqueted and molding thewhole.

4. Method of briqueting finely-divided iron ores, blast-furnace fluedust and the like which consists in forming a binding medium containinglime, alumino-silicates and iron oxid by mixing caustic lime containingalumino-silicates with ferric-hydroxid by wet grinding in the presenceof heat, thereupon mixing the binding medium with the material to bebriqueted and molding the whole.

5. Method. of briqueting finely-divided iron ores, blast-furnace fluedust and the like which consists in forming a binding medium by mixingpulverized highly basic alumino-silicates with ferric-hydroxid and Warmwater, mixing the binding medium with the material to be briquetcd andwith small quantities of fusing-point lowering agents, and molding thewhole.

6. Method of briqueting finely-divided iron ores, blast-furnace fluedust and the like which consists in forming a binding me dium by mixingpulverized highly basic alumino-silicates with ferric-hydroxid and warmWater in the proportion of about one molecule of ferric hydroxid tothree molecules of the bases contained in the basic alumino-silicates,mixing the binding me dium with the material to be briqueted and withsmall quantities of fusingoint lowering agents, and molding the w ole.

7. Method of briqueting finely-divided iron ores, blast-furnace fluedust and the like which consists in forming a binding me- In testimonywhereof have afixed my dium by mixing caustic lime containing signaturein presence of two witnesses.

alumino-silicates with ferric-hydroxid by wet grinding, thereupon mixingthe binding me I WALTHER MATHE SIUS' 5 dium with the material to bebriqneted and Witnesses:

with small quantities of fusing-point 10w- WOLDEMAR HAUPT,

ering agents, and molding the whole. HENRY HAsPER,

